| Onj | 0 | 0 |
| Onkel Kånkel & His Kånkelbär | 0 | 0 |
| Only The Righteous | 0 | 0 |
| Only Worms Left | 0 | 0 |
| Onlybino! | 0 | 0 |
| Onnen Bock | 0 | 0 |
| Onnyk | 4 | 0 |
| Onomeya | 0 | 0 |
| Onutė Gražinytė | 0 | 0 |
| Onutė Narbutaitė | 5 | 0 |
| Onyx Ali | 0 | 0 |
| Onyx Brass | 0 | 0 |
| Onésia Rithner | 0 | 0 |
| Oodaredevil | 0 | 0 |
| Oodelally | 0 | 0 |
| Ookazi | 0 | 0 |
| Ootoro | 0 | 0 |
| Opal Vessel | 0 | 0 |
| Opella Musica | 0 | 0 |
| OpenSoundOrchestra | 0 | 0 |
| Openthebox Trio | 0 | 0 |
| Opera Australia | 1 | 0 |
| Opera Australia Orchestra | 1 | 0 |
| Opera Camerata of Washington | 0 | 0 |
| Opera Colorado Chorus | 0 | 0 |
| Opera Colorado Orchestra | 0 | 0 |
| Opera Factory Freiburg | 0 | 0 |
| Opera Fuoco | 0 | 0 |
| Opera Holland Park | 0 | 0 |
| Opera In Concert | 0 | 0 |
| Opera Multi Steel | 0 | 0 |
| Opera Orchestra of New York | 0 | 0 |
| Opera Philadelphia Chorus | 0 | 0 |
| Opera Philadelphia Orchestra | 0 | 0 |
| Opera Prima | 0 | 0 |
| Opera Rara Chorus | 5 | 0 |
| Opera Restor'd | 2 | 0 |
| Opera Senza | 0 | 0 |
| OperaCréole | 0 | 0 |
| OperaEnsemble | 0 | 0 |
| Operakoret | 0 | 0 |
| Operaorkestret | 0 | 0 |
| Opernchor Leipzig | 0 | 0 |
| Opernchor des Anhaltischen Theaters | 1 | 0 |
| Opernchor des Theater Freiburg | 8 | 0 |
| Opetaia Foa’i | 0 | 0 |
| Ophélie Gaillard | 31 | 0 |
| Opiate | 0 | 0 |
| Opius | 0 | 0 |
| Oppenheimer Analysis | 2 | 0 |
| Oppression | 0 | 0 |
| Oppressor | 0 | 0 |
| Optical*8 | 0 | 0 |
| Optimum Wound Profile | 3 | 0 |
| Optionica | 0 | 0 |
| Opus 20 | 1 | 0 |
| Opus 3 Trio | 0 | 0 |
| Opus Posth | 0 | 0 |
| Opus X | 0 | 0 |
| Opéra Orchestre national Montpellier Occitanie/Pyrénées-Méditerranée | 12 | 0 |
| Or Bareket | 0 | 0 |
| Or Notes Brass | 1 | 0 |
| Oral | 0 | 0 |
| Oralia Dominguez | 3 | 0 |
| Orange Blossom Trail | 0 | 0 |
| Orange Cake Mix | 13 | 0 |
| Orange Kellin | 0 | 0 |
| Orange Poem | 0 | 0 |
| Orange Then Blue | 0 | 0 |
| Orange Vanilla | 0 | 0 |
| Oratnitza | 0 | 0 |
| Oratooriumikoor | 0 | 0 |
| Oratorienchor Karlsruhe | 2 | 0 |
| Oratorienchor Musikvereins Landau | 0 | 0 |
| Oratorio Society of New York | 0 | 0 |
| Orava Quartet | 0 | 0 |
| Orazio Benevoli | 7 | 0 |
| Orazio Maione | 0 | 0 |
| Orazio Sciortino | 0 | 0 |
| Orazio Tuccella | 0 | 0 |
| Orazio Vecchi | 6 | 0 |
| Orbit Service | 0 | 0 |
| OrbitOST | 0 | 0 |
| Orbital Facefuck | 0 | 0 |
| Orbital Gate | 0 | 0 |
| Orcheste symphonique Bienne | 0 | 0 |
| Orchester Adalbert Luczkowski | 1 | 0 |
| Orchester Erich Werner | 0 | 0 |
| Orchester Erwin Halletz | 0 | 0 |
| Orchester Franz Marszalek | 1 | 0 |
| Orchester Hubert Deuringer | 0 | 0 |
| Orchester Joachim Kurzweg | 0 | 0 |
| Orchester M18 | 0 | 0 |
| Orchester Musikkollegium Winterthur | 26 | 0 |
| Orchester Pro Musica Stuttgart | 5 | 0 |
| Orchester Werner Scharfenberger | 0 | 0 |
| Orchester der Bayreuther Festspiele | 31 | 0 |
| Orchester der Berliner Kammeroper | 0 | 0 |
| Orchester der Deutschen Oper Berlin | 35 | 0 |
| Orchester der Deutschen Staatsoper Berlin | 1 | 0 |